RESIDUAL DIPOLAR COUPLINGS IN CROSSLINKED ELASTOMERS INVESTIGATED BY

MAGNETIC EXCHANGE NMR

Xenia Filip, C. Filip1, D. E. Demco2

National Institute for R&D of Isotopic and Molecular Technologies, P.O. Box 700, R-3400 Cluj-Napoca, Romania

1 Francis Bitter National Magnet Laboratory, MIT, Cambridge, Massachusetts2 Institute of Technical Chemistry, RWTH Aachen, Germany

From the viewpoint of NMR crosslinked elastomers exhibit both solid- and liquid-like

features. At temperatures well above the glass transition temperature Tg, the time scale and

amplitudes of molecular motion are liquid-like. However, the presence of both topological

constrains and permanent crosslinks prevents isotopic motion of the chain segments. This

leads to a non-zero average of anisotropic spin interactions, such as dipole-dipole couplings,

which give rise to solid-like properties.

Solid-state one-dimensional proton magnetization-exchange is used to investigate

intergroup residual dipolar couplings in cis-1,4-polybutadiene elastomer. A three-spin model

is employed, in which the CH- and CH2 – group are considered to be coupled by residual

dipolar interactions. The magnetization exchange process between the CH- and CH2-group in

the regime of short mixing time provides valuable insight regarding molecular order. The

spin-system response reflects well-localized dipolar interactions. The residual intergroups

dipolar couplings are measured along the average polymer-chain direction for different

temperatures. The dynamic order parameter along the chains is also evaluated.

107

MAGNETIC PROPERTIES OF xCeO2(0.90Na2B4O7.0.10PbO) GLASSES

Gog Lidia and Culea Eugen

Physics Dept., Technical University of Cluj-NapocaStr.C.Daicoviciu nr.15, 3400 Cluj-Napoca

Glasses containing rare earth ions are of great interest due to their interesting structural,

spectroscopic and magnetic properties.

We studied magnetic behaviour of xCeO2(0.90Na2B4O7.0.10PbO) glasses where x=0.01-

0.15.

Samples were obtained by melting appropriate mixtures of the constitutive oxides at

1300oC for 10 minutes. The melts were rapidly quenched by pooring on a stainless steel plate.

Magnetic susceptibility measurements were performed using a Faraday type susceptibility

balance in the 80-300 K temperature range.

Magnetic data suggest a modified Curie –Weiss type behaviour and may be described

using the formula

= o+C/(T-p)

where o is the temperature independent magnetic susceptibility, C is the Curie constant, T is

the temperature and p is the paramagnetic Curie temperature. The mentioned magnetic

parameters were obtained by fitting the above formula. The C values obtained by this

procedure were used to compute the amounts of Ce3+ and Ce4+ ions in the samples.

108

THERMAL DIFFUSIVITY STUDY ON IRON CONTAININGCaO-P2O5-SiO2 GLASSES AND GLASS CERAMICS

S. Simon*, V. Simon*,D. Dadarlat**, A. Pasca**

*Babes-Bolyai University, Faculty of Physics, 3400 Cluj-Napoca, Romania**National Institute for Research and Development of Isotopic and

Molecular Technologies, 3400 Cluj-Napoca, Romania***Lucian Blaga University, Physics Department, 2400 Sibiu, Romania

Standard photo-pyro-electric (SPPE) measurements were carried out in order to

determine the thermal diffusivity, a, for 45 (3.34 CaO×P2O5)(55-x)SiO2×xFe2O3 glass and

glass-ceramic samples with 0 £ x £ 30 mol %. The values obtained for the investigated

composition range are 0.41×10-6 £ a £ 2.33×10-6 m2/s. Vitroceramic samples obtained by

heat treatment present a similar behaviour of the thermal diffusivity. The temperature

dependence a(T) between 10 and 65oC indicate a linear decrease of 10-8 m2/s degree.

DOPPLER PARAMETERS INVESTIGATION FOR EXPLORATION OF THYROID GLAND

M.Bichis*, T.Suteu**, V.Simon*

*Babes-Bolyai University, Faculty of Physics, 3400 Cluj-Napoca, Romania**Medical Clinic III, 3400 Cluj-Napoca, Romania

Doppler ultrasonography allows the investigation of thyroid gland due to the fact that

physical data as maximal sistolic, minimal diastolic, average velocities, pulsatility and

resistivity indices depend on the thyroid gland metabolism. The ultrasonography

measurements were performed on Doppler and Powerangio (Acuson 2020, Logiq 500)

equipments. The devices were callibrated in same conditions for all patients explored. This

method is preffered, considering the lack of secondary effects. This study points out the

dependence of maximal sistolic velocity on the functional capacity of thyroid gland.

109

MICROWAVE POWER - ASSISTED SAMPLE PREPARATION - EXTRACTION STUDIES

E.Surducan, Camelia Neamtu, V.Surducan, Gabriela Nagy, S.Filip

National Institute for Research and Development of Isotopic and Molecular Technologies, P.O.Box 700, 3400 Cluj Napoca 5, ROMANIA.

The nonconventional microwave power sample preparation is a well-known method.

Our purpose is to use the microwave field distribution to perform probe extraction using

nontoxic polar solvents. This is a new technique because in the classical microwave samples

preparation nonpolar solvents, most of them toxic, are used.

This paper presents our studies on extractions of natural samples by the microwave

power-assisted method, in polar and nonpolar solvents.

STUDIES OF THE MICROWAVE DISTRIBUTIONS IN MICROWAVE POWER APPLICATIONS

E.Surducan, V.Surducan, Camelia Neamtu

National Institute for Research and Development of Isotopic and Molecular Technologies, P.O.Box 700, 3400 Cluj Napoca 5, Romania.

The microwave power applications are very attractive because of the energy saving rate (2 to 100 comparatively with classical processes). The microwave technologies are very elaborate and specific to the nature of the treated materials. One of the most important facts in the elaboration of the technology is the microwave field distribution in the reaction chamber.

This paper presents three categories of applications and the specific microwave field distributions studies: the microwave power adaptations, the microwave field distributions in the cavities of microwave plasma generators and microwave cavities for chemical applications and samples preparation.

110

RELAXATION AND COLLAPSE MECHANISMS OF STEARIC ACID MONOLAYERS AT THE AIR/WATER INTERFACES

Maria Tomoaia-Cotişel*, Janos Zsako*, Gheorghe Tomoaia**,Aurora Mocanu* and Traianos Yupsanis***

*"Babes-Bolyai" University of Cluj-Napoca, Department of Physical Chemistry and Biophysics, 3400 Cluj-Napoca, Romania; **”Iuliu Hatieganu” University,

Orthopaedics Department, 3400 Cluj-Napoca, Romania; ***Aristotelian University of Thessaloniki, Thessaloniki, GR-54006, Greece

Relaxation phenomena in Langmuir monolayers of stearic acid (SA) in the absence

and in the presence of drugs (e.g. deferoxamine: DFO) are studied at several constant surface

pressures, or at constant molecular areas, by recording mean molecular area vs. time curves

or surface pressure vs. time isotherms. The surface pressure vs. molecular area isotherms of

SA monolayers reflect dynamic, rate-dependent measurements [1-6]. A calculation procedure

is proposed to derive kinetic parameters, by using a Prout-Tompkins type equation, adapted

to three mechanisms of relaxation, i.e. micelle formation (1), collapse leading to three- layers

(2), and formation of collapsed bulk phase (3). As observed, during the kinetic run the

mechanism may change, e.g. at a certain moment mechanism (2) replaces mechanism (1).

Kinetic parameters are discussed in terms of molecular structure and physical state of the SA

monolayer. The rate constants for the formation of the new phase, and the integration

constants are correlated to the number of germs of the new formed phase. Data are discussed

in terms of molecular structure, as well as in terms of hydrophobic and hydrophilic

interactions in nanostructured thin films.

1) M. Tomoaia-Cotisel, A. Sen and P. J. Quinn, J. Colloid Interface Sci., 94, 390 (1983)

2) M. Tomoaia-Cotisel, J. Zsako, A. Mocanu, I. Albu, and E. Chifu, Studia Univ. Babes-Bolyai,

Chem., 32, 58 (1987)

3) M. Tomoaia-Cotisel, J. Zsako, E. Chifu and D. A. Cadenhead, Langmuir, 6, 191 (1990)

4) L. J. Noe, M. Tomoaia-Cotisel, M. Casstevens and P. N. Prasad, Thin Solid Films, 208, 274

(1992)

5) J. P. Kampf, C. W. Frank,E. E. Malmstrom, and C. J. Hawker, Science, 283, 1730 (1999)

6) I. Rey-Gomez-Serranillos, P. Dynarowicz-Latka, J. Minones, Jr., and R. Seoane, J. Colloid

Interface Sci., 234, 351 (2001).

111

THE ADSORPTION OF DEFEROXAMINE AT THE AIR/WATER AND HEXANE/WATER INTERFACES

Maria Tomoaia-Cotisel*, Janos Zsako*, Alexandrina Aldea*,Aurora Mocanu*, Iosif Albu* and Ovidiu Minailiuc**

*“Babes-Bolyai” University of Cluj-Napoca, Department of Physical Chemistry and Biophysics, 3400 Cluj-Napoca, Romania; **“Raluca Ripan” Institute of

Chemistry, 3400 Cluj-Napoca

Deferoxamine (DFO) is involved in the assisted transport of iron through interfacial

barriers “in vivo”. It is believed that the interfacial behavior of DFO plays a crucial role in

the mechanism of binding and elimination of iron excess from human body. There is

however no microscopic pictures of DFO orientation at interfaces. This led us to focus on the

behavior of DFO at fluid interfaces. Interfacial tension measurements have been performed

by Wilhelmy plate, du Nouy ring and drop volume techniques. Data demonstrate that DFO

molecules adsorb and accumulate at the interface between the aqueous and organic (hexane)

or air phases. The surface characteristics of DFO in adsorbed films at these interfaces are

determined from interfacial tension isotherms using thermodynamical models [1, 2]. Data are

discussed in terms of different pH-dependent adsorption of DFO molecules at fluid interfaces

and their supramolecular organization induced by the asymmetrical nature of interfaces.

Molecular areas and lateral packing of DFO at different lateral pressures are compared with

theoretical values obtained from molecular geometry of various conformations of DFO

packed in different surface lattices, and the optimum DFO conformations in adsorbed films

are determined. The results have implications concerning the mechanism of iron recognition

by DFO at fluid interfaces that mimics the biological barriers.

1) J. Zsako, M. Tomoaia-Cotisel, A. Mocanu, Csaba Racz, and E. Chifu, J. Colloid Surface

Chem., 2, 37 (1997)

2) M. Tomoaia-Cotisel and P. J. Quinn, “Subcellular Biochemistry, Vol. 30: Fat-Soluble

Vitamins”, edited by Quinn and Kagan, Plenum Press, New York, 1998, pp. 239-242

112

THE STRUCTURE OF MELATONIN FILMS AT FLUID INTERFACES IN THE ABSENCE AND IN THE PRESENCE OF

BOVINE SERUM ALBUMIN

Aurora Mocanu*, Maria Tomoaia-Cotisel*, Janos Zsako*, and Csaba Racz*

*”Babes-Bolyai” University of Cluj-Napoca, Department of Physical Chemistry and Biophysics, 3400 Cluj-Napoca, Romania

Melatonin (N- [2-(5-methoxy-1H-indol-3-yl)ethyl] acetamide or N-acetyl-5-methoxy-

tryptamine) is a hormone of the pineal gland, also produced by extrapineal tissues, that

lightens skin color. The interfacial behavior of melatonin at fluid interfaces is investigated by

interfacial tension measurements performed by Wilhelmy plate, du Nouy ring and drop

volume techniques [1-3], in the absence and the presence of bovine serum albumin. Data

demonstrate that melatonin molecules adsorb and accumulate at the hydrophilic/hydrophobic

interfaces, i.e. between the aqueous and organic (hexane) or air phases. Interfacial tension

isotherms and thermodynamic models are used to determine the surface characteristics,

compression modulus and Gibbs free energy of adsorption for melatonin in adsorbed films at

these interfaces. Data are discussed in terms of the supramolecular organization of melatonin

in thin films induced by the asymmetrical nature of interfaces. Molecular areas at different

lateral pressures are compared with theoretical values obtained from molecular geometry of

melatonin packed in different surface lattices. The results provide a picture of the interfacial

microstructure of melatonin films that should allow interrelation of surface properties

contributions to the transport mechanisms of melatonin at fluid interfaces, that mimics the

biological barriers.

1) M. Tomoaia-Cotisel and P. J. Quinn, “Subcellular Biochemistry, Vol. 30: Fat-Soluble

Vitamins”, edited by Quinn and Kagan, Plenum Press, New York, 1998, pp. 239-242

2) M. Tomoaia-Cotisel, J. Zsako, E. Chifu, A. Mocanu, P. T. Frangopol, and P. J. Quinn, J.

Colloid Surface Chem., 2, 30 (1997)

3) L. J. Noe, M. Tomoaia-Cotisel, M. Casstevens and P. N. Prasad, Thin Solid Films, 208,

274 (1992)

113

COMPUTER MODELLING OF IMPURITIES MIGRATION FROM MULTILAYERED POLYMERS TO FOODSTUFFS

V. Tosa, P.V. Mercea# and O. Piringer#

National Institute for Research and Development for Isotopic and Molecular Technologies, P.O. Box 700, 3400 Cluj-Napoca, Romania

#FABES Forschungs GmbH, Schragenhofstr, 35, D-80992 Muchen, Germany

The development of a numerical method to simulate the diffusion/migration of impurities in and from a multilayer polymeric structure to a liquid is presented. The diffusion equations, initial and boundary conditions are written for the case of a three layer structure in contact with a liquid of finite volume, a case which is often present in food packaging industry. Experimental data obtained in the above configuration compare well with simulated data.

STRUCTURAL EFFECT OF BISMUTH SUBSTITUTION IN Bi2-xMxSr2Ca2Cu3Oz (M = Pb, Cd, Sn, Ge, Sb) SYSTEMS

R.V.F. Turcu, M.Pop, Gh. Borodi*, S.Simon

Babes-Bolyai University, 3400 Cluj-Napoca, Romania*National Institute for Research and Development Isotopic and Molecular

Technology, 3400 Cluj-Napoca, Romania

Samples belonging to Bi2-xMxSr2Ca2Cu3Oz systems were initially obtained as glasses by quickly undercooling from 1200oC to room temperature. Bi was partially substituted by Pb, Cd, Sn, Ge or Sb. In these glass samples were developed crystalline phases by heat treatments applied between 840 and 850 oC for different times from 24 to 170 hours in several stages. The heat treated samples Bi1.8Pb0.2Sr2Ca2CunOz and Bi1.9Sn0.1Sr2Ca2Cu3Oz exhibit superconducting behaviour under 85 K and 115 K respectively. X–ray diffraction patterns show that the Bi1.8Pb0.2Sr2Ca2CunOz sample is a 2221 phase and Bi1.9Sn0.1Sr2Ca2Cu3Oz is a 2223 phase. As the Sn content is increased to 0.2 (Bi1.8Sn0.2Sr2Ca2Cu3Oz sample) one remarks that the superconducting properties disappear, at least above the liquid nitrogen temperature. An interesting structural effect is obtained for this sample and consists in the splitting of certain reflections denoting the transition tendency from the tetragonal system to the ortorombic one. This tendency may be explained by the ionic radius of Sn5+ ion (0.71 A) which is very different from that of Bi3+ ion (1.2 A).

114

CHARACTERISATION OF OXIDIC MATERIALS WITH LUMINESCENT PROPERTIES

Laura Ungur*, Elisabeth-Jeanne Popovici*, Maria Vadan*, Ligia Pascu*, Marilena Vasilescu** and M.Nazarov***

* “Raluca Ripan” Institute of Chemistry, 30 Fântânele, 3400-Cluj-Napoca**"I.G. Murgulescu" Institute of Physical Chemistry of the Romanian Academy

202 Spl. Independentei, Bucureşti, Romania***Technical University of Moldova, Bd. Stefan cel Mare 168, Chişinău,

R. Moldova

Under UV or cathode ray excitation, europium activated yttrium oxide phosphor

shows bright characteristic red luminescence. As a result, Y2O3:Eu phosphor could be used

in the manufacture of coloured fluorescent lamps, cathode ray tubes and plasma display

panels. Phosphor utilisation depends both on powder characteristics and luminescent

properties and sensitivity to various excitation radiation. Photoluminescence (PL) and

cathodoluminescence (CL) properties as well as morpho-structural characteristics strongly

depend on phosphor synthesis conditions. The aim of this paper is to find a correlation

between these characteristics and the synthesis conditions.

Polycrystalline phosphor samples were prepared by thermal synthesis from

homogeneous mixtures containing yttrium oxide (host lattice), Eu2O3 (activator source) and

alkaline earth halides (flux). Phosphors were fired at 1000-1200C and the as prepared

material was washed, dried and sieved.

Phosphor powders were characterised by photoluminescence spectra (PL), XRD and

cathodoluminescent measurements (CL). PL spectra and CL defectoscopy measurements

put in evidence the influence of thermal synthesis conditions on europium incorporation

degree into the yttrium oxide host lattice.

115

TITANATE-BASED CERAMICS FOR IMMOBILIZATION OF RADIOACTIVE WASTE

T.D. Silipaş, E. Indrea, V. Almăşan, I. Bratu, O. Pană, Ana Marian1

National Institute for Research and Development of Isotopic and Molecular Technologies, P.O. Box 700, R-3400 Cluj-Napoca 5, Romania1Babeş-Bolyai University, Faculty Of Chemistry, Cluj-Napoca

The immobilization of radioactive materials in glass or ceramic hosts has been under investigation for many years. One of the most widely known ceramic systems is the SYNROC family, usually a combination of hollandite (BaAl2Ti2O6), perowskite (CaTiO3), zirconolite (CaZrTi2O7) and rutile (TiO2).

We report here a new SYNROC type ceramic system used to immobilize radionuclides by incorporating them as solid solutions in the crystal lattices of various ceramic phases. Reactive powders were properly used to obtain appropriate initial oxides mixture (CaO=11.1 wt%, BaO=5.5 wt%, TiO2=71.2 wt%, ZrO2=6.8 wt%, Al2O3=5.4 wt%). Three different precipitation agents were used: Na2CO3, (NH4)2CO3 and ureea (O=C(NH2)2). The dried powders were calcinated at ca 8000C, wet milled in an alumina jar for 30 min. and heated at different temperatures (to 12000C and 13500C, respectively).

The Zirconolite (CaZrTi2O7 ) and CaTiO3 of perowskite structure, with possible U atoms substitutions on Ca and Zr sites, are the majors crystalline components of SYNROC C + 10 wt% UO2 system.

20 25 30 35 40 45 50 55 60 65 70

2

4

6

8

10

12

14

TiO2

CaTiO3

49.22

CaTiO3

ZrO2

TiO2

CaO

TiO2

BaOTiO2

CaO

CaTiO3

ZrO2

BaO

TiO2

TiO2

68.8847.1936.96

62.65

55.43

53.9147.70

38.45

37.63

34.25

32.75

31.40

29.06

27.88

25.19

inte

nsity

[a.

u.]

diffraction angles 2 [ degrees ]20 25 30 35 40 45 50 55 60 65 70

1

2

3

4

5

6

7

8

9

10

11

12

13

14

CaTiO3

BaO

ZRC

CaTiO3

TiO2

ZRC

CaTiO3

BaO

TiO2ZRC

ZRC

ZRC

BaO

TiO2

CaTiO3

CaTiO334.25

22.66

25.19

61.3258.79

56.78

54.25

52.75

50.74

47.70

46.01

40.6538.96

35.60

33.09

32.25

30.39

28.05

27.20

inte

nsity

[ a

.u. ]

diffraction angles 2 [ degrees ]

Fig. 1. The X-ray diffraction pattern for the SYNROC C ceramic system, calcinated for 4 hours at 8000C

Fig.2. The X-ray diffraction pattern for the SYNROC C ceramic system, sintered for 4 hours at 13000C

116

THE EFFECT OF MAGNETIC FIELD ON Na+ TRANSPORT THROUGH HUMAN ERYTHROCYTE MEMBRANES

C.Bindea, T.Simplăceanu, St.Popescu

National Institute of Research and Development for Isotopic and Molecular Technologies 3.400 Cluj-Napoca Romania, Donath str. No. 65-103; PO Box

700, Tel. 0040-64-185027; Fax 420042

Human erythrocytes were exposed to magnetic field, the intensity domain being 0.59-

0.62T, and the Na+ efflux was measured. It was found that the loading of erythrocytes with

sodium (Na+ erythrocyte) was higher in exposing cells than in controls. By exposing to

magnetic field for 12 hours it result on increase of intracell Na+ by about 40% while after

exposing to more than 12 hours, the intracellular Na+ concentration increased by about 100%.

Due to this particular situation the effect of magnetic field has to be expressed as a relative

effect K/Kcontrol, where K is the difference between the two constants for exposing

samples and controls, respectively.

The rate constant K of Na+ efflux by passive diffusion mechanism increased by about 60%

and by Na+- K+ pump mechanism decreased by about 50%.

117

WHICH RADICALS ARE FORMED BY ELECTROCHEMICAL REDUCTION OF THE NO2 GROUP IN DIHYDRAZID

HYDRAZONE? AN ESR AND DFT STUDY

V.Chiş*, V.Miclăuş*, G.Damian

*Babeş-Bolyai University, Faculty of Physics, 1, Kogalniceanu, RO-3400 Cluj-Napoca, Romania

*Babeş-Bolyai University, Faculty of Chemistry and Chemical Engineering, 11, Arany Janos, RO-3400 Cluj-Napoca, Romania

Dihydrazid-Hydrazone (DHH) contains the o-sulfonamide and nitrofuryl groups

which are expected to show interesting antibacterial properties. This work deals with one of

the paramagnetic products obtained during electrochemical reduction of nitrofuryl group

from DHH compound. The pronounced asymmetry of the ESR spectrum suggests the

superposition of the spectra due to more radicals simultaneously present in the sample and it's

structure with 12 principal lines was simulated assuming the interaction of the unpaired

electron with one nitrogen nucleus and two protons. The best agreement between the

experimental spectrum and the simulated one has been obtained with the following

parameters: g=2.07965, line-width peak-to-peak Hpp=0.19G and the isotropic hyperfine

coupling constants: AN=9.73G, AH(1)=5.07G and AH

(2)=1.01G. Based on the structure of DHH

compound and ESR parameters deduced by simulation we propose the free radical which

could be responsible for the hyperfine structure in the experimental spectrum. The

experimental coupling constants and unpaired spin density determined by us are comparable

with those corresponding to others radicals in which the odd electron is delocalized on a

similar fragment.

The geometry and hyperfine coupling constants of the radical have been studied by ab

initio and DFT calculations, performed with Gaussian program. Molecular structure of the

radical has been optimized by different methods with a variety of basis sets The calculated

isotropic hyperfine coupling constants are in good agreement with experiment, being

consistent with a planar structure of the radical at nitrogen site.

118

UNPAIRED SPIN DENSITY DISTRIBUTION OF THE TYROSYL RADICAL IN BIOLOGICAL SYSTEMS

V.Chiş*, F.Mureşan*, Anna Lisa Maniero**, Marina Brustolon**

*Babeş-Bolyai University, Faculty of Physics, 1, Kogalniceanu, RO-3400 Cluj-Napoca, Romania

**Universita Degli Studi di Padova, Dipartimento di Chimica Fisica, Via Loredan 2, Padova, Italia

X-band, cw-EPR, EchoEPR and ENDOR spectroscopies are used to characterize the

tyrosyl radical produced in a gamma-irradiated single crystal of L-Tyrosine-hydrochloride, at

room temperature.

The radical is found to exists in two slightly different conformations, both of them

being very close to the original position of the parent molecule in the crystal. Hyperfine

coupling tensors of the protons at 3 and 5 positions of the aromatic ring are used in the two

center dipole approximation to estimate the carbon-proton bond length and the unpaired spin

density at the corresponding carbon atoms of the ring. One of the β-methylene proton

coupling is used to derive the conformation of the CH2 group of the radical with respect to the

aromatic ring.

Hyperfine coupling tensors are calculated in the limits of INDO approximation, using

an AM1 optimized geometry of the radical. A comparison is given of the tyrosyl radical

unpaired spin density pattern in different biological systems.

119

SPECTROSCOPICAL INVESTIGATION OF SOME

CALIX[n]ARENES DERIVATIVES UTILISABLE AS METAL

EXTRACTING AGENTS

Cristina Ciocan, Elisabeth-Jeanne Popovici, Crina Dan, Maria Vădan,

Rodica Grecu and N. Popovici

“Raluca Ripan” Institute of Chemistry, 30 Fântânele, 3400-Cluj-Napoca

ROMANIA

Calix[n]arenes are polinuclear compounds that act as selective complexation agents

for electrical charged or neutral species. The high complex-formation ability of calix[n]arenes

offers them large utilisation possibilities in the manufacture of sensitive membranes,

elaboration of selective extraction methods for various cations and anions, realisation of

modern metal recovery procedures and for environmental protection.

The purpose of this study is to present our attempt to prepare some O-acetilated p-tert-

butil-calix[n]arene in order to test their ability to co-ordinate precious metallic ions.

Tert-butil-calix[n]arene and their corresponding acetate-derivative were prepared by

specific procedures. The as prepared calix[n]arenes were investigated by elemental analysis

and various spectroscopic methods such as RMN, MS-GC, UV-Vis and FTIR.

The ability of some of the above mentioned compounds to extract precious metallic

ions from aqueous solutions was tested.

120

CAN ZERO MAGNETIC FIELD AFFECT THE ELECTRICAL CHARGE OF PROTEINS IN LIPOPROTEINS STRUCTURE

DURING HUMAN BLOOD AGEING IN VITRO ?

D. Ciorba*, V. V. Morariu**

*Diagnosis and Treatment Centrum, Biochemistry Laboratory, Cluj-Napoca, Romania

** National Institut for Research and Development of Isotopic and Molecular Technologies, P.O. Box&700, R 3400, Cluj-Napoca, Romania

Purpose: The natural magnetic field or the geomagnetic field (GMF) is a physical factor of the normal environment. The natural variations of this field can affect the health of man. Consequently we may expect that the lack of GMF or zero magnetic field (ZMF) could influence the living processes as well, possibly even more than the present fluctuations of GMF. Our investigation involved the exposure of the blood to the natural environment and to zero magnetic field. The purpose of our work was to observe the influence of ZMF on proteins from lipoproteins structure. For this purpose, we performed the electrical separation of lipoproteins, by electrophoresis. At the same time we determined the cholesterol and triglicerides concentrations by spectrophotometric methods. Methods: Compensation of the static component of natural geomagnetic field (GMF) was done in a Helmholtz coil system. The reducing factor of GMF was around 100x. This particular condition was called zero magnetic field (ZMF). The investigations were carried out on the human blood collected from apparently healthy donors. The blood sample was divided in equal volumes. Three control samples were kept in normal conditions i.e. in the geomagnetic field and the others were exposed to the ZMF conditions, at room temperature. We have repeated the analytical procedures after 24h, 48h and 72h. Aging of the blood proceeded during this time. The analysis of cholesterol and triglicerides was performed by using a Cobas-Mira auto-analyzer. The electrophoresis in agarose gel is based on the lipoproteins mobility in serum. Blak Sudan dye is used to specifically color these lipoproteins fractions. The methods essentially correspond to the recommendations of International Federation for Clinic Chemistry (IFCC). Results: The cholesterol and triglicerides fluctuations in the serum during the first 24h of ageing of blood, implies a cholesterol and trigliceride exchange between the cells and the serum compartment. The results indicate the different binding of lipid components in serum, during the ageing of blood in GMF compared to ZMF. Thus, in ZMF there is a significant increase of chylomicrons density which is the fraction with the lowest electrical charge, while in GMF there is a significant increase of alphalipoproteins, the fraction with the highest electrical charge. Anyway, the increase of chylomicrons in ZMF is much more accentuated in the increase of alpha lipoproteins in natural magnetic field.Conclusions: In vitro exposure of human blood to ZMF conditions leads to a significant cell aging and cellular lysis proceed faster compared to GMF conditions. It has been found the ZMF influence on proteins in the serum is manifested partly on the electrical charge of protein components and partly on their dimension. The analysis of lipoproteins mobility in blood serum aged in vitro, also contributes to better image regarding the aging process of blood and underlines again the ZMF influence on the electrical charge of proteins. This may occur by the influence on proteolysis, oxidation processes, etc.

121

MAGNETIC BEHAVIOUR OF OXIDE LEAD-BISMUTHATE GLASSES CONTAINING IRON IONS

R. Pop, M. Coldea*, I. Cosma**, V. Simon*

Physics Department, University of Civil Engineering, Bucharest, Romania

*Faculty of Physics, Babeş-Bolyai University, 3400 Cluj-Napoca, Romania

**Physics Department, Technical University, 3400 Cluj-Napoca, Romania

The investigated samples belong to xFe2O3(100-x)[3Bi2O3·2PbO] system (1≤ x ≤ 20

mol %) and were obtained by melting of suitable mixtures at 1100 oC for 10 minutes in air,

followed by fast undercooling to room temperature. The magnetic measurements carried out

with a Faraday balance in the temperature range 80 – 300 K indicate the lack of magnetic

order only for the sample containing 1 mol % Fe2O3 while for 5 ≤ x ≤ 20 mol % an

antiferomagnetic type ordering is evidenced. The paramagnetic Curie temperature linearly

decreases with Fe2O3 content in the studied composition range. According to magnetic

moment values calculated from the experimental data the valence state of iron ions changes

from Fe3+ to Fe2+ as x increases from 1 to 20 mol % Fe2O3. The ratio Fe2+/Fe3+ was

determined for each sample.

122

HEMOGLOBIN AND HUMAN BLOOD ADSORPTION ON SILVER COLLOIDAL PARTICLES: SURFACE ENHANCED

RESONANCE RAMAN STUDIES

*S. Cîntă Pînzaru, **S. Cavalu, *N. Leopold, ***W. Kiefer

*Babes-Bolyai University,Physics Faculty, Optics and Spectroscopy Dept. Kogalniceanu 1, RO 3400 Cluj-Napoca, Romania

**University of Oradea, Faculty of Medicine and Pharmacie, Biophysics Dept., 1 Dec. Square 10, RO-3700 Oradea

***Institut für Physikalische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany

Due to the high sensitivity and selectivity combined with the fluorescence quenching,

surface enhanced Raman spectroscopy has been recently applied to investigate single

molecule behaviour.[1, 2]. Evidencing single molecule opens new directions in the applied

spectroscopy, mainly for the biological active samples or in-vivo studies.

In the present work, surface enhanced resonance Raman spectra (SERRS) of hemoglobin and

freshly acquired integral human blood samples on colloidal silver particles have been

recorded and discussed. It is known that the hemoglobin molecule presents a strong

fluorescence background at the green light (514.5 nm) excitation. Conventional Raman

technique being inadequate, SERRS technique overcomes such difficulties by quenching

fluorescence. SERRS spectrum of integral human blood was successfully obtained and

compared to that one of hemoglobin. A time dependence study was also carried out. The

main hemoglobin marker bands (1610, 1586, 1568, 1375, 1167, 957, 761 and 674 cm-1) were

observed in the SERRS spectra of blood. Vibrational analysis and potential biological

applications are further discussed.

References:

1. K. Kneipp, H. Kneipp, I. Itzkan, R.R. Dasari, M. S. Feld, Chem. Rew. 1999, 99,

2957-2975.

2. Hongxing Xu, Erik J. Bjerneld, M. Kall, L. Börjesson, Phys. Rew. Lett., 83, 21,

1999, 4357.

123

SELECTIVE EXCITATION PROFILE APPLIED IN RAMAN AND SERS STUDY OF BIOLOGICAL SYSTEMS

*S. Cîntă Pînzaru, **S. Cavalu, *N. Leopold, *O. Cozar, ***W. Kiefer

*Babes-Bolyai University, Physics Faculty, Kogalniceanu 1, RO 3400 Cluj-Napoca, Romania

**University of Oradea, Faculty of Medicine and Pharmacie, Biophysics Dept., 1 Dec. Square 10, RO 3700 Oradea, Romania

***Institut für Physikalische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany

In the early 1980s, research groups began to study surface enhanced Raman scattering

(SERS) of biological molecules in order to obtain new structural-functional information1. The

effect of adsorption interactions on the structure and function of biomolecules adsorbed onto

a metal surface is an important issue with respect to many fundamental processes as well as

in applied areas. For example, many biological processes involve protein interactions with

membrane surfaces and the possibility of modelling these interactions at a metal electrode has

already been suggested by bioelectrochemists2. In the medical field, an understanding of the

behaviour of proteins at surfaces is important with respect to implants and prosthetic devices.

SERS may provide means for probing protein interactions and functions.

By choosing the laser line in resonant or non-resonant conditions for the molecule, we can

obtain additional information. Thus, the surface enhanced resonance Raman scattering

(SERRS) effect can complete information by taking into account several major advantages

over the techniques of SERS or resonance Raman scattering. The phenomenon of

fluorescence quenching combined with resonance enhancement leads to a totally huge

enhanced signal, greater than using only one of these techniques. Also, the SERRS sharp

spectral bands obtained enables discrimination of individual molecular species in mixture.

In this respect, vibrational spectral response in resonant or non-resonant conditions for

several free or adsorbed species like lactoperoxidase, hemoglobin, human blood and

cytochrome c, are presented and discussed.

References

1. T. M. Cotton, J. H. Kim, G. D. Chumanov, J. Raman Spectrosc. 22, 729, (1991).

2. T. M. Cotton, in Spectroscopy of Surface, edited by R. J. Clarck, R. E. Hester (1988).

124

SCALING CHARACTERISTICS OF THE STRUCTURE OF HUMAN HAEMOGLOBIN

Aurel Coza*, Vasile V. Morariu**

*Faculty of Physics, Babes-Bolyai University, Cluj-Napoca, Romania**Department of Biophysics and Environmental Physics, National Institute for Research and Development of Isotopic and Molecular Technologies, 3400 Cluj-

Napoca, P.O.Box 700 Romania, E-mail: vvm@L40.itim-cj.ro

The structure of proteins was described in terms of fractal characteristics both in

relation to the position of the aminoacids and properties such as the hydrophobicity of the

aminoacids. The methods of analysis involved typical procedures for measuring the fractal

dimension. The goal of our study was to characterise the series of the temperature factors (Tf)

of the haemoglobin heavy atoms (all excepting hydrogen).

The method used for analysis was the Detrended Fluctuations Analysis (DFA). DFA

consists in integration of the series and dividing the integrated series in intervals of lag n,

every interval being fitted with a line (yn(k)). For different lag of n calculate F(n)={1/N

[y(k)-yn(k)]2}1/2 , the value of F(n) typically will increase with n, and the slope of the

plot relating F(n) with n gives the scaling exponent .

We have calculated the scaling exponent from the series representing Tf of heavy

atoms of human haemoglobin (chains A and B). We found that the haemoglobin is

characterised by a complex DFA pattern, the slopes of the fitting lines (i.e. the scaling

exponents) of the DFA plot depend on n. It can be seen that haemoglobin is characterised by

three slopes i.e. three scaling exponents. These three scaling exponents correspond to the

three structural levels of protein (primary, secondary and tertiary). In this respect we have

obtained =0.96, =0.81 and =1 from the three levels. We have also found that mutant

haemoglobin display a different pattern from that of normal haemoglobin, in this case only

one or two slopes appeared and the values of the scaling exponents which are different from

that of normal protein. This changes in the vibrations pattern may be involved in the

misfolding or the dysfunction of these proteins.

125

EPR INVESTIGATIONS OF NON COVALENT SPIN LABELLED

CYTOCHROME C AND OVALBUMIN

G. Damian1, S. Cavalu2, M. Dânşoreanu3, C. M. Lucaciu4

1 “Babes-Bolyai” University, Dpt. of Physics, RO-3400 Cluj-Napoca, Romania2 University of Oradea, Faculty of Medicine, RO-3700, Oradea, Romania3 University of Medicine and Pharmacy “Iuliu Hatieganu”, Dept. of Biophysics,

RO-3400 Cluj-Napoca, Romania4 University of Medicine and Pharmacy, “Iuliu Haţieganu”, Dept. of Biophysics

and Radiopharmacy, RO-3400 Cluj-Napoca, Romania

Nitroxyl radicals exhibit a number of chemical and physical properties that make them extremely useful molecules for studying biochemical systems, especially the metalloporphyrins. The EPR spectrum can be affected by the motional constrains and orientation of the spin label in the system, by the polarity of the system and by the presence of other species in the system such as reducing agent and paramagnetic ions. Conversely, a spin label can affect the properties of system [1].

The aim of this work was to investigate the Tempyo spin label as a report group for the interactions and the conformational changes of Cytochrome c and Ovalbumin, as function of pH. Solutions containing cytochrome c and ovalbumin labelled with Tempyo nitroxide radical (3-carbamoyl-2,2,5,5-tetramethyl-3-pyrolin-1-yloxy), molecular ratio 1:1 were prepared in phosphate buffer at different pH values (in the range 2.5 – 12) and subsequently lyophilized. The X-band EPR spectra of the solid samples were recorded at room temperature and analyzed by using a program that is available to the public through the Internet (http://alfred.niehs.nih/LMB) for obtaining the magnetic characteristic parameters. The spectra are similar with those of other noncovalently spin label porphyrins in frozen solution at very low temperatures [2]. This behavior indicated a possible spin-spin interaction between the hemic iron and the nitroxide group. The changes in the EPR spectra as function of the pH are discussed in terms of conformational changes of the proteins.

References[1] “Spin Labeling:Theory and Applications” (L. J. Berliner, Ed.), Academic Press,

New York, 1976[2] Budker, V., Du, J.-L., Seiter, M., Eaton, G., R., Eaton, S., S., Biophysical J.,

68(1995) 2531

126

ALUMINA MEMBRANES USED AS MOLECULAR FILTERS FOR HUMAN RED BLOOD CELLS AND BOVINE SERUM

ALBUMIN

Gh. Mihailescu, Stela Pruneanu, Silvia Neamtu, Liliana Olenic

National Institute of R&D for Isotopic And Molecular Technology, P.O.Box 700, Cluj-Napoca 3400, Romania

Nanoporous alumina membranes were electrochemically prepared in sulfuric or

phosphoric acidic aqueous solutions. The oxidation process was performed at low

temperature (4...80 C) for about 3 hours. The stirring of the electrolyte during oxidation, was

a necessary condition for the formation of an ordered structure oxide. After preparation, both

the residual aluminum and the barrier layer were removed from the backside, by chemical

etching. At the end of these steps we obtained nanoporous membranes having pores’ diameter

between 20 and 100 nm.

These membranes were following used as molecular filters for human red blood cells

and bovine serum albumin. The filtration efficiency was evaluated by UV-Vis absorption

spectroscopy. A very good filtration efficiency was obtained with the 20 nm porous

membrane, that gave rejection factors higher than 0.92.

127

SCALING IN THE TEMPERATURE FACTOR SERIES OF CYTOSKELETON PROTEINS

*Lavinia Gheorghe, **V.V.Morariu

*Faculty of Physics, Babes-Bolyai University, Cluj-Napoca** Department of Biophysics and Environmental Physics, National R&D

Institute for Isotopic and Molecular Technologies, 3400 Cluj-Napoca, P.O.Box 700, Romania, (corresponding author)

The subject of our investigation is two of the cytoskeleton proteins, namely actin and myosin. The myosin heads bind to actin filaments and "walk" along actin filaments providing the molecular mechanism for muscle contraction. The purpose of this work was to investigate the properties of the temperature factors series characterising the mobility of the atoms in these proteins, excepting the hydrogen atoms. These data were collected from the Protein Data Bank and represent an information provided by X ray analysis of crystallised protein. It is of high interest to characterise these spatial series as they clearly may offer information about what kind of order exists within the protein structure. While the X-ray provides the spatial structure of the protein, the analysis of the temperature factor series may offer new clues about the distribution of the mobility characteristics within such a functional structure. The present work employs the Detrended Fluctuation Analysis (DFA) in order to detect the nature of the fluctuation in these series. The DFA scaling exponent is 0.5 if the series is random and >0.5 when fractal. We have analysed various chains and fragments of the proteins as well as in the operational actin-myosin complex form. The resulting data are included in table below.

No Protein complex, protein or protein fragment Scaling exponent1 Ca ATP actin-myosin

-myosin S1 fragment -actin

1.071.06

2 Acto-myosin -myosin heavy chain -myosin light chain 1 -myosin light chain 2 -actin

0.980.750.761.25

3 Papain digested myosin -myosin heavy chain without S1 fragment -myosin light chain 1 -myosin light chain 2

0.970.931.01

The results show that both actin and myosin are characterised by a scaling exponent close to one, which corresponds to the well known 1/f noise. At the same time the myosin light chains and actin revealed different exponents 3/4 and 5/4 respectively. According to present models of scaling, the exponents having a value of 1/4 or multiples of 1/4 are due to the optimisation of the system in respect to their role. This may suggest that the proteins have been optimised by evolution to an optimum state of mobility to accomplish their role.

128

FRACTAL ASPECTS OF THE SEA HARE MYOGLOBIN STRUCTURE

Adriana Isvoran*, Laura Unipan**, V. V. Morariu***

*University of The West Timisoara, Department of Physics, Bd. Parvan No. 4, 1900-Timisoara, E-Mail: Adii@Galileo.Uvt.Ro

**University of Agricultural Sciences Timisoara, Cl. Aradului No. 169, 1900-Timisoara,

*** National Institute for Research and Development of Isotopic and Molecular Technology, P.O. Box 700, 3400-Cluj Napoca 5 and, Faculty of Physics, Babes-

Bolyai University, Cluj-Napoca

In this paper we determine the fractal dimensions of the sea hare myoglobin backbone and its

complexes with azide and imidazol using X-ray diffraction data. In order to determine the fractal

dimension of a protein backbone we plot the length, L, of the backbone, measured as a stepwise

connection of straight lines between the Cα atoms for different intervals of m residues, versus m. The

fractal dimension of the backbone is determined from the slope of the log(L)-log(m) plot. We found

that the log(L)-log(m) plots show two linear portions for the uncomplexed myoglobin and also for its

complexes with azide and imidazol. The slopes of the two linear portions (and also the fractal

dimensions) are almost the same for the myoglobin in the free conformation and for its complexes.

This means that the conformational changes of the myoglobin when it reacts with the substrates or

their analogues do not affect the backbone of the protein to a significant extent.

129

THE INFLUENCE OF SALTS ON PARALLEL DNA TRIPLE HELIX FORMATION, CONTAINING GT IN THE THIRD

STRAND

C. M. Munteana, J. Liquierb and E. Taillandierb

aNational Institute of Research and Development for Isotopic and Molecular Technologies, R-3400 Cluj-Napoca, P.O. 5, Box 700, Romania,

<cmuntean@l30.itim-cj.ro>bLaboratoire de Spectroscopie Biomoléculaire, CNRS URA 1430, UFR Santé

Médecine Biologie Humaine, Université Paris-Nord, 74, rue Marcel Cachin, 93017 Bobigny, France

Over the past few years, oligonucleotides have received increased attention as a potential new class of pharmacologically active compounds [1]. The so-called antigene strategy is based on local triple helix formation via the binding of an oligonucleotide to the major groove of double-helical DNA [1].

This work is a study of UV spectroscopy, concerning the stability of DNA in triple

helix, in the presence of Zn2+ and Na+ ions. The third strand of this triple helix contains guanines and thymines and has a parallel orientation, with respect to the polypurinic strand of the Watson-Crick double helix. In this study we have used the triple helix forming oligonucleotide 5'-GGTGGGTGGTG - linker - CTCCTCCCTCCT - linker - AGGAGGGAGGAG-3', where the linker = pO(CH2CH2O)3p. In the formed triple helix,

triplets are characterized by a purine / pyrimidine motif. Double and triple helix stabilities were measured by thermal DNA melting experiments. The melting temperature (Tm) was

evaluated as the temperature of half-association (or half-dissociation) of the formed complexes determined by the first derivative of the melting curve [1]. In the case of triplexes, a biphasic profile has been found, with a first triplex to duplex transition and a second transition duplex to open strand.

References1. Zhou-Sun, B.-w, Sun, J.-s, Gryaznov, S. M., Liquier, J., Garestier, T., Hélène, C., and Taillandier, E. (1997) A physico-chemical study of triple helix formation by an oligodeoxythymidylate with N3'- P5' phosphoramidate linkages, Nucleic Acids Research, 25: 1782-1787.2. Ouali, M., Letellier, R., and Taillandier, E. (1996) Correlations between the sugar-backbone conformation and the third strand orientation in triple helices, J. Mol. Struct., 377: 57-74.

130

INFRARED SPECTROSCOPY OF DNA MOLECULES

C. M. Munteana, E. Fagarasanb

aNational Institute of Research and Development for Isotopic and Molecular Technologies, R-3400 Cluj-Napoca, P.O. 5, Box 700, Romania,

<cmuntean@l30.itim-cj.ro>bUniversity of Medicine and Pharmacy, Cluj-Napoca, Romania

The IR spectrum of a nucleic acid gives in the 2000-500-cm-1 region around 40 well defined absorption bands that appear at different positions with different relative intensities and dichroic ratios depending on the nucleic acid geometry [1]. Different types of information can be obtained by IR spectroscopy. For example, it is possible to characterize molecular geometry, using what is usually called IR "marker bands" which are conformation sensitive (wavenumber and/or relative intensity and/or polarization of the absorption) [2]. These bands can show the existence of a conformational transition when different factors such as temperature, hydration, concentration, and nature of counterions are varied.

In this work we have used dezoxyribonucleic acid (DNA) from calf thymus, sodium salt (Sigma) to study the IR markers of DNA molecules. The samples were investigated by Fourier transform infrared (FTIR) spectrometry (Nicolet 205 FTIR spectrometer).

In the following, the main vibrations observed in the spectral region between 1800 and 700 cm-1 are described. Four domains can be observed: between 1800 and 1500 cm-1

absorption bands due to the stetching vibrations of double bonds in the base planes; between 1500 and 1250 cm-1 bands due to the base-shugar entities, strongly dependent on the glycosidic torsion angle; between 1250 and 1000 cm-1 strong absorptions of the phosphate groups and of the sugar; below 1000 cm-1 bands due to the vibrations of the phosphodiesteric chain coupled to vibrations of the sugar [2].

AcknowledgementsWe want to thank to Silvia Stamate for help in taking the FT-IR spectra.Research experience gained during the training period at the University Paris-Nord,

France is greatfully acknowledged by one of us (C.M.M.).

References

1.Liquier, J. and Taillandier, E. (1996) Infrared spectroscopy of nucleic acids, in H. H. Mantsch and D. Chapman (Eds.) Infrared Spectroscopy of Biomolecules, Wiley-Liss, Inc.: 131-1582. Taillandier, E. and Liquier, J. (1992) Infrared spectroscopy of DNA, in "Methods in Enzymology", vol. 211, Academic Press, Inc.: 307-335.

131

THE BACTERIA GROWTH MONITORED BY LIGHT SCATTERING TECHNIQUE.

* Silvia Neamtu, *I. Turcu, *C.V.L. Pop, **E. Boldizsar

* National Institute for Research and Development of Isotopic and Molecular Technologies, POBox 700, Cluj-Napoca 5, email: silvia@l40.itim-cj.ro

** Microbiology Department, University of Agricultural Sciences and Veterinary Medicine, Cluj-Napoca

The bacteria growth evaluation is carried out by establishing the germ densities/cm3

nutritive medium at different time period during 24 h incubation time, in the samples drawn

from the bacteria suspension.

The methods currently employed assume either a laborious technique of successive

dilution or the turbidity comparison between the bacteria suspension and nephelometric Mc

Farland scale (BaSO4 concentration scale, that correspond to known bacteria densities). Our

aim is to present the advantages of the light scattering technique as a quantitative method to

characterize the bacteria multiplication for their whole evolutive cycle.

Our method consists in passing a He-Ne laser beam of 632,8 nm wavelength

through 1 mm thick suspension. The intensity of scattered beam is detected at small angle by

a photodiode, the signal is amplified and transferred to a PC computer by an A/D converter.

The scattered centers are bacteria cells; the increase of their densities induce an augmentation

of the detected radiation intensity.

This method is one of the easiest ways to characterize the concentration of the diluted

cell suspensions. A very large range of the cells density (10 -6-10-1 volume fraction) can be

detected. The large number of recorded data (in our experiments 12 000) taken with a high

frequencies (20Hz) assure an accurate determination of scattered centers densities.

In order to monitor the bacteria growth a Mc Farland calibrating scale and a grown-up

bacteria suspension dilution scale were determined. The data recorded are processed in two

ways: the analysis of the mean values versus concentration and fluctuation around the mean

values versus concentration respectively. A good linearity of the curve in the range of 10-4-10-

3 volume fraction was obtained .

The unpatogene bacteria growth process during 24 h incubation time determined from

the calibrating scales is presented.

132

LOCAL CHARACTERIZATION OF TIME SERIES BY DETRENDED FLUCTUATION ANALYSIS (DFA)

C.V.L. Pop, I. Turcu, Lorelai I. Ciortea

National Institute for Research And Development of Isotopic And Molecular Technologies, P.O.Box 700, 3400 Cluj-Napoca 5,

E-Mail:Popcl@L40.Itim-Cj.Ro

The data obtained in experiments performed on biophysical systems generally have

significant temporal non-stationer fluctuations, and are very long time series (e.g. 400000

data or more). Such a time series can be obtained monitoring light intensity scattered at small

angles by the human erythrocyte suspensions during the sedimentation process.

The idea of detrended fluctuation analysis (DFA) is to compute the dependence of the

standard error of a linear interpolation of time series on the size of the interpolation segment.

This DFA method has proven useful in revealing the extent of long-range correlation in time

series, but by supplying a global information this method can be irrelevant for very long time

series such as mentioned above.

The purpose of our work was to investigate very long time series of the sedimentation

process by applying in two ways the DFA method on a significantly short range of time

series. This was applied, on the one hand for successive domains without crossing; on the

other hand by crossing domains simply moved with a percent of their length.

These two methods based on the computation of a scaling exponent by means of a

modified root mean square local analysis of a time series can be used for quantifying the

correlation property in non-stationary time series.

We processed the long time series obtained for suspended human erythrocytes

obtained by using the light scattering technique with a 10-mW He-Ne laser at 632,8-nm

wavelength. The analysis of the dynamic evolution of the correlation along the whole

sedimentation process by applying this two methods is presented.

133

CONTROL SYSTEM TO DELIMIT THE GRASSING AREA

St. Popescu, T. Simplăceanu, C. Bindea

National Institute of Research and Development for Isotopic and Molecular Technology 3.400 Cluj-Napoca Romania, Donath street No. 65-103; PO Box

700, Tel. 0040-64-185027; Fax 420042

The system responds to two major needs:

it secures a rational exploitation of the grass field;

it prevents the animal from escaping from the boundary surface to the neighboring ones;

The above mentioned targets are accomplished by means of a assembly of one electric

structure build by two components:

a). A high tension electronic generator which provides 8 10 KV pulses every 1.5

seconds.

b). A conductor cable which surrounds the area may take the geometric shape of the

grassing land and it may be up to 5 Km long.

The system relies on two factors:

on the biological effect of the weak electric power of high voltage on the skin and

muscles of a living organism;

on the conditioned reflex the animal that has got in touch with the system acquires;

The result might be profitable considering the low cost of the surveillance of the

animal groups and from the point of view of an ecological exploitation of the grass fields.

134

LIGHT SCATTERING TECHNIQUE DETECTION OF SUSPENDED PARTICLES AT VERY LOW CONCENTRATION

I. Turcu, C.V.L. Pop, Silvia Neamtu

National Institute for Research and Development of Isotopic and Molecular Technologies, P.O.Box 700, 3400 Cluj-Napoca 5, email: iturcu@l40.itim-cj.ro

Light scattering technique is one of the easiest ways of characterizing the

concentration of diluted suspensions of microparticles. For suspended human erythrocytes,

for example, the light intensity scattered at small angles has a maximum at a hematocrit

(volumic fraction) of about 1,510-3 for 1-mm thick suspension. At higher concentrations the

efficiency of scattering decrease, the maximum being the consequence of the balance

between the augmentation effect when the concentration of scattering centers increase and the

decreasing effect due to the multiple scattering.

In our paper we investigate the very low suspension concentration range (ppm), the

aim of the work being to demonstrate that the light scattering technique is appropriate for

detection and characterization of suspensions of microparticles.

There are two distinct ways that can be used to characterize the microparticles

suspension behavior: One of them is the analysis of the mean value dependence versus

concentration and another one it is the fluctuation versus concentration. The second method

can be made by:

(1) detrended fluctuation analysis (DFA) in long range correlation area

(2) analysis of the slow and fast fluctuations rate.

We focus on the analysis of these methods in order to find which best characterize the

low concentration of diluted microparticles suspensions especially which can assure the best

resolution at low concentration (ppm).

Light scattering experiments were performed on cell and inorganic particle

suspensions using a 10-mW He-Ne laser at 632,8-nm wavelength. The light scattered by

suspension is detected by a photodiode and the signal is amplified and transferred to a PC

computer by an A/D converter.

135

A FLUID FLOW MODEL FOR DIGITIZED EXPERIMENTAL DATA

*I. Turcu, **C. Vamos, *C.V.L. Pop, *Silvia Neamtu

* National Institute for Research and Development of Isotopic and Molecular Technologies, P.O.Box 700, 3400 Cluj-Napoca 5, email: iturcu@l40.itim-cj.ro

** Romanian Academy, “T.Popoviciu” Institute of Numerical Analysis, P.O.Box 68, 3400 Cluj-Napoca 1, Romania

Digitized experimental data obtained in experiments on biophysical systems have in

general significant temporal fluctuations. Usually the informations related to the investigated

phenomena are obtained from the mean values of the data. The common attitude is to reduce

as much as possible the dispersion of the experimental data, this dispersion being associated

with different types of random noises.

The attitude has changed in the last few years and a lot of researches have shown that

for some relevant systems the fluctuations have important temporal correlations. A lot of

information about the system can be obtained by decoding the behavior of correlated

temporal fluctuations. The aim of the present paper is to propose a physical model able to

catch in a few parameters the dynamic characteristics of the investigated phenomena.

The idea is to associate to fluctuating values of the dynamic parameters (recorded by

some experimental set-up) the position of a corpuscular particle in a fluid flow. The model

use space-time coarse-grained averages that can be defined and satisfy balance equations

even for a single particle. In this way, we can characterize the mezoscopic dynamic properties

of the system without a direct study of the detailed dynamical behavior of the associated

particles.

The model is applied on data obtained from a light scattering experimental set-up. If a

collection of microparticles in suspension is irradiated with coherent light, the scattered

intensity has a very complex dynamic pattern known in the literature as laser speckle

phenomenon. Spatial domains of mainly constructive interference are boarded by dark,

destructive interference domains. The interference pattern has also a relatively complex

temporal behavior dictated by the dynamics of the suspended microparticles. The light

intensity is detected by a photodiode and the signal is amplified and transferred to a PC

computer by an A/D converter.

Light scattering experiments were performed with a 10-mW He-Ne laser at 632,8-nm

wavelength.

136

THE INTRANET STRUCTURE FOR A RESEARCH INSTITUTE IN PHYSICS

Mihai Jalobeanu

National Institute for Research and Development of Isotopic and Molecular Technologies, P.O. Box 700, R-3400 Cluj-Napoca 5, Romania

Since its beginning, Internet mainly addresses to academic community. Moreover, the World Wide Web development, at CERN, between 1989 and 1992, was a result of the scientist communication needs, in a period when scientific research became, much more, a question of cooperation between professionals, as well as, between teams. The ability to share easier the experimental data, or mathematical models, to review progress reports, and to remotely verify a result, are nowadays essential for modern science, not only in the High Energy Physics researches. Consequently, for many years, academic cooperation and training were in the top of Internet applications.

Between1995-1997, a new, and very frequently used, buzzword - Intranet - became a key-notion for a company information system. It is a question to apply, and somehow to restrict, the use of Internet tools, inside the company's computer network. Intranet means a LAN, which includes at least a Web server, with some Web-content access policies (i.e. a separation between public available data, and protected information for internal use only).

The presence on the Web is considered as a survival condition for each company, and especially for a research team. For an Intranet, it must be accomplish presenting a different facet for an outside visitor, comparatively with that available for a team member. Moreover, the local Web server access, and its content available as HTML documents, can be powered through the Web forum software, providing the virtual seminar facilities, in so called Web cooperative environment.

The INCDTIM local area computer network, designed in 1994-1995, and based on a Linux server, was developed splitting the Class C network (193.231.25) into 8 sub-nets with 32 IP addresses each. The main idea was to have separate LAN's for each of the institute laboratories, providing the corresponding group read/write rights, as well as account-based user Home site ownership.

Transition to the Web cooperative environment can be done for each sub-network (each laboratory), using the local Web server and defining a proper access policy. The overall Web content must be classified into the public available documents, and private - protected ones, eventually, with different degrees of protection. With such a classification, and using different already installed Web forums, all the institute members could share their knowledge, discussing their ideas and results.

137